Earthquake Rocks Santa Cruz County, Felt Across Bay Area

A magnitude 4.9 earthquake struck Santa Cruz County in the early hours of Thursday morning, impacting residents throughout the wider Bay Area. The United States Geological Survey (USGS) confirmed the quake occurred around 1:41 a.m.

Epicenter and Shaking Intensity

The earthquake’s epicenter was located near Boulder Creek, at a depth of approximately 6.2 miles. Residents closest to the epicenter, as well as those in cities like San Ramon, Fremont, Burlingame, and Los Gatos, reported experiencing strong shaking.

Widespread Reports of Shaking

According to USGS data collected through “Did You Feel It?” responses, residents in numerous other Bay Area locations also felt the quake. These included Oakland, San Francisco, Berkeley, Milpitas, Walnut Creek, Pleasant Hill, San Leandro, Dublin, and Richmond, who reported experiencing weak to light shaking.

Aftershock Potential

The USGS anticipates possible aftershocks in the days following the initial earthquake. They stated, “There will likely be smaller aftershocks within the next week, with up to 9 magnitude 3 or higher aftershocks.”

USGS Aftershock Forecast

The USGS forecast indicates a 60% probability of a magnitude 3.0 or higher aftershock occurring within the next seven days. There is a 14% chance of a magnitude 4.0 or higher quake, and a 2% chance of a magnitude 5.0 or greater aftershock.

The USGS also noted a low probability that the initial quake could be a foreshock to a larger event – a magnitude 4.87 or greater quake. They emphasized that their forecasts are dynamic, particularly within the first 72 hours after a mainshock.

“Our forecast changes as time passes…These changes happen because of three things: the usual decrease of aftershocks as time goes on, larger aftershocks that trigger more activity, and changes in forecast modeling due to ongoing data collection,” the USGS explained.